Lamellar separator

ABSTRACT

A lamellar separator includes a lamellar pack which is formed from vertically oriented first plates (1) having a first corrugation in the vertical plane, where the lamellae (10,11) of said plate inclined to the vertical plane form vertical boundaries for substantially horizontal flow channels, and vertically oriented second plates (2) corrugated in the horizontal plane, arranged on either side of each first plate and in contact therewith. The flow channels are defined horizontally by the corrugation peaks of the second plates, and the vertical rise and fall channels for separate pollutants are defined by the second plates (2) and the corrugation peaks (22) of the first plates. The corrugations (1,2) of the first plates are preferably triangular. The first plates (1) and the second plates (2) are preferably put together such that the corrugation peaks (12) of the first plate lie behind the corrugation peaks (22) of the second plate (2).

TECHNICAL FIELD

The invention relates to a lamellar separator comprising elongatesubstantially planar lammelae extending substantially horizontally intheir longitudinal direction, for vertically separating substantiallyhorizontal flow passages for a liquid which is to be purified, saidpassages being inclined to the horizontal plane in their transversedirection, for gravitational removal from the lamellae of heavy and/orlight pollutants separated from the liquid.

BACKGROUND ART

In lamellar separators, a main flow is taken in a path between lamellae,whereon suspended particles gravitationally separated from the mainflow, as well as miscible liquids, are collected in the boundary layeradjacent the lamellar surfaces, from where they can slide awaygravitationally from the lamellae without being essentially disturbed bythe main flow. If the lamellae have substantial length in their inclineddirection, there is a risk that the separated material in the boundarylayer assumes such thickness that the main flow is disturbed, or thatthe latter once again entrains material from the boundary layer.

One ambition will therefore be to arrange the lamellae with smallextension in the direction of inclination, simultaneously as theinclination is sufficiently large so that material transport in theboundary layer in the direction of inclination will be relatively rapid,while the vertical distance between adjacent lamellae will be as smallas possible to minimize the length of the flow passages.

This would however result in that the lamellar stack obtained a verysmall width and large height, alternatively that the required lamellarpack must be formed from a plurality of such stacks, whereby baffleelements would need to be inserted between the stacks to preventundesired flow patterns. Examples of such modus operandi are illustratedin the Swedish published application No. 7101307-2.

It will be understood, however, that in such apparatus it is notpossible to afford vertical channels, which are difficult to disturb,for both light and heavy material which has left the lamellae, oralternatively that it would not be possible to prevent through flowbetween adjacent lamellar packs.

It is furthermore a known situation that lamellar packs for lamellarseparators tend to get a very complicated structure, if subdivision ofthe flow paths into a plurality of parallel paths with small area isstriven after.

PURPOSE

One purpose of the invention is, therefore, to propose a lamellarseparator eliminating or reducing the disadvantages which are associatedwith structures already known. An object is thus to propose a lamellarpack with a structural fabrication which is very simple, and allows thesimple manufacture of the elements incorporated as well as simpleassembly of the elements to a finished pack. The invention furthermorehas the object of providing a lamellar separator in which the tendencyof separated material to collect on the lamellar surfaces is avoided,and which affords undisturbed vertical passages or channels for lightand heavy separated pollutants.

SUMMARY OF THE INVENTION

The inventive lamellar separator includes a lamellar pack comprisingelongate substantially planar lamellae extending substantiallyhorizontally in their longitudinal direction for vertically definingsubstantially horizontal flow passages or channels for a liquid which isto be cleaned. The flow passages are inclined to the horizontal plane intheir transverse direction for gravitational removal from the lamellaeof heavy and/or light pollutants separated from the liquid.Distinguishing for the invention is that there are vertically orientedfirst sheets or plates made with a first corrugation in the verticalplane, the portions thereof which are oblique to the vertical plane formsaid lamellae. Vertically oriented second sheets or plates corrugated inthe horizontal plane are disposed on either side of each first plate andin contact therewith.

In a preferred embodiment, the first and second plates are put togethersuch that the corrugation peaks on each first plate are behind thecorrugation peaks on the second plates and vice versa. According to afurther development of the invention, the first plate can have a secondcorrugation extending substantially perpendicular to the firstcorrugation, the second corrugation then having lower height andpreferably shorter pitch than the first corrugation. The secondcorrugation of the first plate can be origamically folded at the peaksof the first corrugation.

The separator can be made such that the first corrugation of the firstplate has a width which is substantially equal to the pitch, thelamellar surfaces having, for example, a slope of 60° to the verticalplane.

The corrugation on the second plate can have a width or depth which issubstantially equal to the pitch. The width and pitch of the corrugationon the second plate preferably being equal to the width and pitch of thefirst corrugation on the first plate.

In a preferred embodiment of the invention, the corrugation of the firstplate can have a pitch of 3 to 50 mm, preferably about 8 mm, and thesecond corrugation of the first plate can have a pitch attaining toabout 1/5 of the pitch of the first corrugation.

The inventive lamellar separator will have special use in the separationof metal carbide particles as well as oil and grease from cuttingliquids. In such a case it can be suitable to allow the corrugation ofthe first plate to have a pitch of the order of magnitude of 8 mm toallow minimization of the lamellar pack size, taking into account themetal carbide particles which are present in machining metal carbideobjects or machining with the aid of metal carbide tools.

If it is assumed that the first corrugation on the first plate has apitch of 8 mm, that the main flow passages have a length of 300 mm andthat the active flow passage area of the lamellar pack is 7.5 dm², metalcarbide particles with a size of 5μ can be separated at a flow of 11liters per minute. If the pitch of the corrugation on the first plate is3 mm instead, metal carbide particles with a size of 2μ can be separatedat a flow of hardly 5 liters per minute.

Use will naturally also be found for the invention for other purposesthan purifying cutting liquid containing metal carbide particles. Itshould thus be quite clear that the invention is also to the purpose fortreating waste water of a general kind, and that a prominent feature ofthe invention is that it allows a limited volume for the lamellar pack,while simultaneously enabling simple production of the separate elementsin the lamellar pack, as well as enabling simple assembly of theelements into said pack. Due to the orthogonal embodiment and verticalorientation of the lamellar pack it allows simplified installationthereof in a liquid container, which can thus also have orthogonalconfiguration.

The invention is defined in the appended patent claims, and will bedescribed in detail in the following in the form of an example, withreference to the appended drawing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical section through a lamellar pack incorporated in thelamellar separator in accordance with the invention.

FIG. 2 is a horizontal section taken along the line 2--2 in FIG. 1.

FIG. 3 is a detail of a first corrugated plate incorporated in thelamellar separator.

FIG. 4 is a schematic view of a lamellar separator in which a lamellarpack according to FIGS. 1 to 3 can be incorporated.

FIG. 5 is a schematic section taken along the line 5--5 in FIG. 4.

FIG. 6 illustrates the boundary layer of the lamellar pack in aschematic vertical section transverse to the first plates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 4, a lamellar separator includes an orthogonallamellar pack 100, arranged in a vessel the lower portion 103 of whichreceives separated heavy material and the upper portion 104 receivesseparated light material. An inlet hopper 101 leads a flow 30 of theliquid to be cleaned horizontally through a lamellar pack 100. An outletchamber 102 takes the flow 30 from the lamellar pack 100 and thecontainer. The lamellar pack 100 is formed from corrugated plates 1 and2 with the corrugations alternatingly on the cross and with orthogonalconfiguration, the resulting lamellar pack 100 also being orthogonal inits construction, for being accommodated in an orthogonal container. Theinlet of the pack is restricted vertically by upper and lower baffleplates 105 and 106, respectively (see FIG. 5), and the side plates 107and 108 of the container can adjoin tightly to the outer plates 2 of thelamellar pack. The pack 100 is shown in detail in FIGS. 1 and 2. FIG. 1is a vertical section parallel to a plane normal to the flow directionof the main flow 30. FIG. 2 is a section taken along the line 2--2 inFIG. 1.

The lamellar pack comprises corrugated plates 1 and 2 arrangedalternately with the main corrugation of the plates 1 in the verticalplane and the corrugation of the plates 2 is in the horizontal plane.The corrugated surfaces 10, 11 of the plates 1 form vertical boundariesto the flow passages for the main flow 30, while the corrugation peaks22 of the plates 2 form a restriction of these flow passages in thehorizontal direction. The main flow is subdivided into a plurality ofpartial flows 30, each being led through a horizontally directed channeldefined by the peaks 22 of the plate 2 and the corrugation surfaces orlamellae 10, 11 of the plate 1. In the preferred embodiment, illustratedin FIGS. 1 and 2, the plates 1 and 2 are adapted for meshing with eachother so that the peaks 12 of the plates 1 lie behind the plane throughthe peaks 22 of the plates 2. Light pollutants in the flow 30 will risetowards the underside of the adjacent lamella 10 or 11, there to comeinto the boundary layer of the lamellar surface and subsequently glideupwards along the lamellar surface 10 or 11, by degrees to leave thelamella at the corrugation peak 12, where the light pollutant flow 31has departed from the effective through-flow cross section by a goodmargin. In a corresponding mode, heavy pollutants in the flow 30 willgravitate down towards the adjacent lamella 10 or 11 to come into theboundary layer closest to said lamellar surface, glide down by gravityalong it and out to the corrugation peaks 12, where the flow 32 of heavypollutants leaves the respective lamella 10,11 at a substantial distancefrom the main flow 30. The corrugation surfaces of the plates 2 and thecorrugation edges 12 of the plates 1 define vertical rise and fallchannels for the separated pollutant flows 31 and 32, respectively.Since both these flows 31,32 are by definition hydrophobic, noreblending of the flows 31,32 ought to occur.

FIG. 3 illustrates a detail of a plate 1. In FIG. 1 can be seen thelamellae 10 and 11 of the plate 1 and the corrugation peaks 12 betweenthe lamellae 10 and 11. It is clearly apparent that the plate 1 has beengiven a second corrugation, which is here illustrated as a zigzagcorrugation comprising the lamellar surfaces 20, 21. The corrugationpeaks 12 of the plate 1 are formed origamically, so that the valleysbetween the surfaces 20,21 of the second corrugation on the firstlamella 10 will lie horizontally further out than the peaks between thesurfaces 20,21 on the lamella 10. As a result of the origamic folding,the flow of light pollutants, which streams upwards on the underside ofthe lamella 11 in a channel defined by the surfaces 20,21 of the secondcorrugation, will lie displaced both in the direction of the edge 12 andin the horizontal direction from the flow of heavy pollutants which flowdownwards along the lamella 10 in the valley between the surfaces 20,21of the second corrugation. There is thus afforded a further possibilityof keeping the flows 31,32 in the vertical channels separate from eachother.

FIG. 6 is a schematic fragment of FIG. 1, where it is apparant that eachhorizontal flow channel is given an effective cross section 40surrounded by a boundary layer 41 defined by the lamellar surfaces 10,11and the corrugation peak 22 of the plate 2. Since plates 1 and 2 furthermesh with each other by a distance t, a safety margin is hereby definedso that the distance between the flow 40 inside the boundary layer 41and the plane through the corrugation peaks 12 of the first plates willbe sufficiently large so that disturbances in the flow along the path 40are hardly likely to affect the rise and fall flows 31 and 32 in thevertical channels. The distance t between the plane through the tops 12of the first plates and the tops 22 of the second plates is to advantageof the same order of magnitude as the thickness of the boundary layer41.

To advantage, the plates 1,2 can be made from compression mouldedplastics sheets with a thickness of 0.1 mm, for example.

Furthermore, the lamellar pack 100 can be provided with a vibratoracting vertically, with a vibrational amplitude which is less,preferably considerably less, than the pitch between the corrugationpeaks on the first plate. By "pitch" is intended the distance betweenadjacent similarly directed corrugation peaks on a plate.

Certain sedimented substances, e.g. grinding particles can be given acertain structural strength--a kind of increase in viscosity, due to theinner friction between the particles--when the particles are stacked ontop of each other. This can result in a deposit on the lower surfaces ofthe lamellar channels, which by degrees blocks the passages. Suchclogging can be prevented by a lamellar pack being given a reciprocatingvertical movement by vibration. The lamellae then move relative to theliquid and a displacement occurs in the vertical direction. The liquidis forced to flow over the tips of the horizontal lamellae. The speedand amplitude of the movement can be adjusted so that a desiredentrainment of sedimented substance occurs.

The movement must be adjusted so that sedimented particles do not whirlup into suspension again--the result shall be that the particles by themovement are taken out into the lamellar profiles of the verticalchannels where they can sink freely.

In separating light substances, e.g. mineral oils in water, a lamellarpack in accordance with the above is very effective. Oil collects in theupper portions of the horizontal flow channels. The vertical movementfacilitates the attachment of small oil droplets to larger ones, whichmore easily ease away from the horizontal fold and rise up to thevertical channels.

When separating oil in water, a vertical transport of large and smalloil drops is easily obtained. The oil content can be very high at a highpoint in a vertical channel for a certain volume, but in spite of thisthere is rather a lot of water present. During the oscillating movementof the lamellar pack, the speed at which the water content in the oillayer sinks down through the oil layer is increased. The result is thusa decreased water content in the separated oil.

Especially when machining cast iron and cast steel, the cutting andcleaning emulsions get their emulsified oil saturated with small steelresidues to such an extent that the specific weight of the polluted oilrises towards 1. When the oil then separates from the emulsion, andsmall drops gather together into larger ones, the steel particlesentrained by the oil can be repulsed. In the lamellar pack describedhere, the heavy particles can sediment freely without stopping up thechannels.

The principles, preferred embodiments and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Theembodiments are to be regarded as illustrative rather than restrictive.Variations and changes may be made by others without departing from thespirit of the present invention. Accordingly, it is expressly intendedthat all such variations and changes which fall within the spirit andscope of the present invention as defined in the claims be embracedthereby.

What is claimed is:
 1. A lamellar separator containing a lamellar packcomprising elongate, substantially planar lamellae extendingsubstantially horizontally for vertically defining substantiallyhorizontal flow passages or channels for a liquid which is to bepurified, said flow passages in their transverse direction beinginclined to the horizontal plane for gravitational removal from thelamellae of heavy and/or light pollutants separated from the liquid,said separator including an inlet, a liquid outlet and at least oneoutlet for separated material, said lamellar pack including verticallyoriented first sheets or plates having a first corrugation in thevertical plane, portions of the first plates inclined to the verticalplane of said plates forming said flow passages, said lamellar packfurther including vertically oriented second plates corrugated in thehorizontal plane, said second plates being disposed on either side ofeach first plate and being in contact therewith whereby the liquid flowis subdivided into a plurality of partial flows each passing through thehorizontal flow passages defined by peaks of the second plates andcorrugation surfaces of the first plates.
 2. Lamellar separator asclaimed in claim 1, wherein each of the first plates has a secondcorrugation extending substantially at right angles to the firstcorrugation, the second corrugation having less height and shorter pitchthan the first corrugation.
 3. Lamellar separator as claimed in claim 2,wherein the first corrugation of the first plates has a substantiallytriangular form, the second corrugation of the first plates isorigamically folded at the peaks of the first corrugation.
 4. A lamellarseparator as claimed in claim 1, wherein the first and second plates arearranged such that corrugation peaks of the first plates lie behindcorrugation peaks of an adjacent second plate.
 5. A lamellar separatoras claimed in claim 4, wherein the corrugation peaks of the first andsecond plates lie behind each other by a distance corresponding to thethickness of the boundary layer in the flow passages.
 6. A lamellarseparator as claimed in any one of claims 1-4, wherein the firstcorrugation of the first plates has a width which is substantially asgreat as the pitch.
 7. A lamellar separator as claimed in any one ofclaims 1-4, wherein the corrugation of the second plates hassubstantially as great width as pitch and has the same width and pitchas the first corrugation of the first plates.
 8. A lamellar separator asclaimed in claim 6, wherein the corrugation of the second plates hassubstantially as great width as pitch and has the same width and pitchas the first corrugation of the first plates.
 9. A lamellar separator asclaimed in claim 2 or 3, wherein the first corrugation of the firstplates has a width which is substantially as great as the pitch.
 10. Alamellar separator as claimed in claim 9, wherein the first corrugationof the first plates has a pitch of 3 to 50 mm and the second corrugationof the first plates has a pitch of about 1/5 of that of the firstcorrugation.